Flexural Creep Behavior of High-Density Polyethylene Lumber and Wood Plastic Composite Lumber Made from Thermally Modified Wood

Abstract

The use of wood plastic composite lumber as a structural member material in marine applications is challenging due to the tendency of wood plastic composites (WPCs) to creep and absorb water. A novel patent-pending WPC formulation that combines a thermally modified wood flour (as a cellulosic material) and a high strength styrenic copolymer (high impact polystyrene and styrene maleic anhydride) have been developed with advantageous viscoelastic properties (low initial creep compliance and creep rate) compared with the conventional WPCs. In this study, the creep behavior of the WPC and high-density polyethylene (HDPE) lumber in flexure was characterized and compared. Three sample groupings of WPC and HDPE lumber were subjected to three levels of creep stress; 7.5, 15, and 30% of the ultimate flexural strength (Fb) for a duration of 180 days. Because of the relatively low initial creep compliance of the WPC specimens (five times less) compared with the initial creep compliance of HDPE specimens, the creep deformation of HDPE specimens was six times higher than the creep deformation of WPC specimens at the 30% creep stress level. A Power Law model predicted that the strain (3%) to failure in the HDPE lumber would occur in 1.5 years at 30% Fb flexural stress while the predicted strain (1%) failure for the WPC lumber would occur in 150 years. The findings of this study suggest using the WPC lumber in structural application to replace the HDPE lumber in flexure attributable to the low time-dependent deformation when the applied stress value is withing the linear region of the stress-strain relationship.

Advances in Wood Composites II

“…In this context, the application of wood plastic composites in marine applications sounds very interesting. Alrubaie et al [39] presented an innovative wood plastic composite lumber made from thermally modified wood. Its overall performance was compared to the performance of high-density polyethylene lumber (HDPE).…”

Lifetime prediction under dead-load long-term creep test and models analysis of wood-plastic composites for building materials

“…The deflection of the samples was then slowly observed in the time interval between 50 h (3000 min) and 1000 h (60,000 min). It also found that the creep strain tended to increase with enhanced levels of loading [11,17,20]. According to the tests under different load levels of the ultimate flexural strength, it was found that the deflections of the rPP are 2.45, 4.65 and 6.68 mm whereas the WPC samples values of 1.53, 2.41 and 3.37 mm, respectively.…”

Upcycling of waste artificial turf forhigh‐performancewood‐plastic composites

“…8,9 As a kind of biomass materials, woodplastic composites combine the advantages of wood and plastic, which are used in environments where traditional wood products cannot be used for solving the problem that wood products are easy to rot and deform after absorbing water in a damp environment. [10][11][12][13] The use of plastic waste with a single component as the matrix for wood-plastic composites has been considered an effective method to the plastic circular economy. However, due to the poor compatibility of each component in the WAT and the poor dispersibility of wood flour (WF) in the WAT matrix, the use of WAT in the woodplastic composite material is a challenging task.…”

“…With its renewability, biomass resources have been widely concerned and have been used in the preparation of various materials 8,9 . As a kind of biomass materials, wood‐plastic composites combine the advantages of wood and plastic, which are used in environments where traditional wood products cannot be used for solving the problem that wood products are easy to rot and deform after absorbing water in a damp environment 10–13 . The use of plastic waste with a single component as the matrix for wood‐plastic composites has been considered an effective method to the plastic circular economy.…”